Efficient ZnO aqueous nanoparticle catalysed lactide synthesis for poly(lactic acid) fibre production from food waste

This study demonstrates the feasibility of poly(lactic acid) fibre production using fermentative lactic acid from food waste. Poly(lactic acid) was synthesized through ring-opening polymerization, in which the precursor lactide was produced by a novel catalytic method. Zinc oxide aqueous nanoparticle (30–40 nm) dispersion was applied as efficient catalyst due to its large surface area and rapid equilibrium between polymerization and depolymerization. Under optimal reaction conditions, lactide was produced at yields of 91–92% within 8 h, significantly improving the synthesis efficiency compared to the conventional tin-based catalytic method. The pure lactide product facilitated the conversion of food waste derived lactic acid to high molecular weight poly(lactic acid) (150,000 g mol−1), which was subsequently spun to fibres with promising tensile and thermal properties for potential applications in textile and bioplastics.